The invention provides a mutant of Monascus purpureus; and its use in preparing yellow pigments.
Historically, the genus Monascus has been wildly used as food additives in China and other Asiatic contries. U.S. Pat. Nos. 4,442,209, and 5,457,039 have disclosed the utilization of Monascus sps. in the production of red, yellow and orange pigments which are served as the major sources of natural pigments. According to U.S. Pat. No. 5,429,943, the ratios between the red and yellow pigments among the Monascus pigments are mostly 1:1, and the hue of the Monoscus pigments shows red. Therefore, the Monascus pigments are useful in the production of red pigments. The relevant prior art references disclosing the utilization of genus Mocascus in the production of Monascus yellow pigments include: U.S. Pat. No. 5,013,564, wherein a reduction reaction is used to treat Monoscus pigments; and JP 55088696 and 81053589, wherein the cultural conditions, such as pH value or cultural medium, are controlled to achieve the purpose of producing Monascus yellow pigments.
Blanc et. al. (International Journal of Food Microbiology; 27, (1995), 201-213) found that Monascus sps. were capable of producing a fungal toxin (citrinin), which received considerable attention to the safety of the Monascus pigments. JP 7274978 discloses a method to reduce the amount of citrinin (lower than 1 ppm) by a mutant strain. However the pigments produced by the method are mostly red pigments and the yellow pigments can only be obtained by an additional processing treatment. Although Monascus sps have been widely used in the production of red pigments, a Monascus strain which could produce a higher proportion of yellow pigments and a lower amount of citrinin had not been found until now.
The present invention provides a mutant of Monascus purpureus designated as Monascus purpureus M011, or the mutant thereof, which can produce yellow pigments directly in a solid or liquid medium using cheap natural raw materials without any further processing steps, and a very low amount of citrinin produced thereby.
The invention also provides a method for producing yellow pigments by using the novel mutant or mutants thereof of the present invention.
The invention further provides a yellow pigment composition, containing a low amount of citrinin, prepared by the novel mutant of the present invention or mutants thereof
The present invention provides a mutant of Monascus purpureus designated as Monascus purpureus M011, which is obtained by mutagenizing Monascus purpureus CCRC 31499 (also named as Monascus anka ATCC 16360, CBS 283.34, IFO 4478, and KFCC 11832) and screening therefrom.
Monascus purpureus CCRC 31499 is available from the Food Industry Research and Development Institute (FIRDI) in Hsin-Chu, Taiwan. The invention further comprises the mutants of Monascus purpureus M011 of the present invention, which can be prepared by using any conventional relevant mutation techniques, e.g., treating with chemical or physical mutagens (such as UV light, X-ray, or xcex3-ray) and chemical substances (such as N-methyl-Nxe2x80x2-nitro-N-nitrosoguanidine).
The strain of Monascus purpureus M011 of the invention has been deposited in the Food Industry Research and Development Institute, Taiwan, on Sep. 18, 2000, and assigned the accession No. CCRC 930045; and has also been deposited with the American Type Culture Collection, (ATCC, 10801 University Boulevard, Manassas, Va. 20110-2209, USA) on Sep. 22, 2000 in accordance with the Budapest Treaty, and assigned the accession No. ATCC PTA-2496.
According to the present invention, the method for producing yellow pigments by using Monascus purpureus M011 or a mutant thereof can be performed by fermentation in a solid or liquid cultural medium.
According to the present invention, all known as carbon and nitrogen sources can be used in the above medium. Natural material is the preferred embodiment of the invention, wherein the carbon source includes, but not limited to rice powder, corn starch, rice starch, wheat starch, glucose, maltose, sucrose, and glycerol, or combination thereof; and the nitrogen source includes, but is not limited to soybean powder, soybean albumen, digestive albumen, yeast extract, corn steep liquor, glutamic acid, ammonium chloride, and potassium nitrate, or combination thereof.
According to one preferred production method of the present invention, the pH of the cultural medium is from 2 to 8.
According to the present invention, the amount of citrinin in the yellow pigment fermentation products is less than 1 ppm, preferably less than 0.3 ppm, and most preferably less than 0.2 ppm.
According to the present invention, the produced yellow fermentation liquid is useful as an additive to food. The yellow pigments in the fermentation liquid can be purified by various conventional techniques, e.g., the ionic exchange method as taught in IP 07216248, the method by controlling the solvent and pH values as taught in JP 61281158, and the ethanol purification methods used in JP 54033535, 53069887, and 52034985. In addition, yellow pigments can be extracted from fungi by conventional techniques, e.g., the method taught in JP 03254686. The yellow pigments fermentation liquid of the present invention can be used as additives for example, to food, cosmetics and pharmaceutical products, after a further purification process.
The following examples are used for illustration, but not for limiting the invention.